It seems likely that you are pregnant. The problem is idnetifying when you conceived. I'll need to know the usual duration of your menstrual cycle before you started using birth control pills. If your cycle doesn’t last more than 25 days, then you may have conceived in August. But if your cycle last more than 25 days, you probably didn’t conceive in August but sometime in May or June. I recommend you to visit your gynecologist for an ultrasound examination to confirm the pregnancy and to determine the possible pregnancy age according to the embryo’s dimensions. Both the data from ultrasound examination and the date of your last period/cycle's duration will give us a more clear picture about the time and date of possible conception.